Differential Disconnect

Took the truck into the dealer for a humming sound in the front end. Guessing that the ADD (automatic differential disconnect) is not disengaging. Will find out today and I'll post up the findings.
8k miles on the truck.

 

I bet $10 the Dealer says the problem is related to you removing the bumper.

I have not heard of this issue before, subd.

 

Was the humming constant or just at specific speeds?

 

Checked everything and was told that it must be the suspension. I was expecting this, the problem with all of the electronic crap is that most technicians just plug the ECU in and if it shows no error they assume that there is no problem and thats that! I'm doing some research as to what else it could be, the Icon suspension is actually installed at a few dealers as an option and carries the factory warranty.
Just for clarification: The hum is exactly like a manual hub'd truck would sound if you were driving around with the hubs engaged. When the hum is present if the 4wd is engaged it goes away, hence it has to be in the drive line. Also the tech explained that if you're having trouble engaging or disengaging the electronic 4wd that the clutch pedal has to be pressed down VERY hard to make it function. Any input from you all is appreciated. I will call up to Toyota corp. HQ and try to discuss this problem with a engineer.